Technology is already known for achieving stereoscopic observing by separately providing a left-eye video and a right-eye video that are two-dimensional video with parallax to the left eye and right eye of a viewer. One example of a method for providing a left-eye video to just the left eye and a right-eye video to just the right eye is a shutter system which alternatingly displays the left-eye video and right-eye video, and opens and closes the left and right shutters of spectacles worn by the viewer, synchronized with the alternating display. Another example is a polarization system in which the left-eye video and the right-eye video are given different polarization orientations; the polarization filters of spectacles worn by the viewer allow only one image to pass. There are also systems which use a device equipped with an optical system that provides images independently to the left and right eyes of the viewer, such as a HMD (Head Mounted Display) (Patent Document 1, for example).
Movies, games, etc. and various types of stereoscopic video content are distributed using this sort of stereo video technology. Also, this sort of stereo video is used in training the extraocular muscles and kinetic vision, and in practice for vision recovery and visual performance.